Rare sighting of massive stars that are actually touching

Ars Technica : A team of astronomers using the Very Large Array has spotted an extremely rare system called an overcontact binary, in which the two stars are directly sharing material. The system is both the most massive and the hottest every spotted, with a combined mass 57 times that of the Sun and each star reaching more than 40 000 K. The two stars are just 12 million km apart and orbit their common center of mass in just over 24 hours. The team, led by Leonardo Almeida of the University of São Paolo, Brazil, estimates that the stars are each sharing 30% of their material. Overcontact binaries are rarely found because the arrangements usually don’t last long; they either merge into a single star and possibly explode as a long-duration gamma-ray burst, or they maintain separation and each explodes as a supernova before collapsing into a black hole.